KR20230113561A - Process for hydroformylation of olefins in homogeneous phase - Google Patents

Abstract

The present invention is a process for preparing an aldehyde by hydroformylation of an olefin with synthesis gas over a transition metal complex catalyst, wherein, in a first process step, the olefin is treated with a metal and a ligand bound thereto in the presence of a water-miscible solvent. The pressure, temperature and ratio of the solvent and aqueous catalyst solution are controlled so that the hydroformylation is carried out in a homogeneous single-phase reaction solution, and in the second process step, the temperature and/or lowering the pressure, the homogeneous reaction solution from the first reaction step is converted into a two-phase process solution and at least a portion of the organic phase is separated from the aqueous phase.

Description

Process for hydroformylation of olefins in homogeneous phase

The present invention is a process for preparing an aldehyde by hydroformylation of an olefin with synthesis gas over a transition metal complex catalyst, wherein, in a first process step, the olefin is treated with a metal and a ligand bound thereto in the presence of a water-miscible solvent. The pressure, temperature and ratio of the solvent and aqueous catalyst solution are controlled so that the hydroformylation is carried out in a homogeneous single-phase reaction solution, and in the second process step, the temperature and/or by lowering the pressure, the homogeneous reaction solution from the first reaction step is converted into a two-phase process solution and at least a portion of the organic phase is separated from the aqueous phase. will be.

Further functionalization of olefins by hydroformylation in the presence of metal catalysts has been known for a long time. As the primary product of this reaction, an aldehyde having one more carbon atom than the reactant olefin is obtained. These aldehydes can be used as such or, preferably as such, as additional reactants to produce a variety of useful downstream products. Important industrial downstream products of the actual hydroformylation are, for example, butanol or 2-ethylhexanol, obtainable via an aldehyde intermediate from propene as an olefin starting material, obtained from aldehydes, for example by hydrogenation. There is alcohol available. The end products of hydroformylation are used in various ways, as solvents, as intermediates for the production of detergents and detergents, lubricants or plasticizers for plastics.

Although the basic interrelationships of the conversion of olefins to aldehydes are well known, large-scale processes are still many, as the economic efficiency of the overall process is characterized by a complex interplay of reaction conditions, reactant conversion, desired selectivity, catalyst life, and recovery. of the optimization approach occurs. In particular, catalysts and their efficient use are very important in such matrices, since the cost of the metals normally used far exceeds the cost of the other reaction participants.

This has led to the development of many different large-scale process options, the various process designs of which can be found in numerous documents of the patent literature.

For example, WO 2004 024 661 A1 describes a process for the catalytic hydroformylation of olefinically unsaturated compounds containing 3 to 24 carbon atoms, wherein at least one unmodified catalyst containing a metal of groups 8 to 10 of the periodic table of the elements is a catalyst , wherein the hydroformylation is performed in the presence of a cyclic carbonic acid ester of the formula: wherein the proportion of the carbonic acid ester is 1% by weight or more of the reaction mixture.

R ¹ , R ² , R ³ , R ⁴ , the same or different at each occurrence, is H or substituted or unsubstituted aliphatic, alicyclic, aromatic, aliphatic-alicyclic, aliphatic having 1 to 27 carbon atoms - an aromatic, cycloaliphatic-aromatic hydrocarbon radical,

n is 0 to 5;

X is a divalent substituted or unsubstituted aliphatic, cycloaliphatic, aromatic, aliphatic-cycloaliphatic or aliphatic-aromatic hydrocarbon radical having from 1 to 27 carbon atoms.

In another patent document, EP 1 529 771 A1 describes the preparation of 8(9)-formyl-tricyclo[5.2.1.0 ^2.6 ]dec-3-ene by hydroformylation of dicyclopentadiene in a heterogeneous reaction system using an aqueous solution. A method for producing, wherein a water-soluble organic phosphorus (III) compound in a complex bond containing a transition metal compound of group VIII of the periodic table of elements is reacted with synthesis gas at a temperature of 70 to 150 ° C. and a pressure of 0.5 to 10 MPa, Methods are disclosed wherein certain sulfonated triarylphosphines are used as water-soluble organic phosphorus (III) compounds.

Another possibility for the reaction of cyclic compounds with multiple double bonds is disclosed in DE 10 2006 004 318 A1. 3(4),7(8)-dihydroxymethyl-bicyclo[4.3.0]nonane by hydroformylation of bicyclo[4.3.0]nona-3,7-diene followed by hydrogenation. A method for producing, wherein bicyclo[4.3.0]nona-3,7-diene is complexed at a temperature of 70 to 160° C. and a pressure of 5 to 35 MPa and containing an organophosphorus compound in an excess of organophosphorus compound By reaction with syngas in a homogeneous organic phase in the presence of a transition metal compound of group VIII of the periodic table of elements followed by hydrogenation of 3(4),7(8)-bisformyl-bicyclo[4.3.0]nonane , 3(4),7(8)-dihydroxymethyl-bicyclo[4.3.0]nonane.

This solution known from the prior art can offer further improvement possibilities, in particular with regard to the possible conversion efficiency, the simplicity of separating the reaction mixture, and the reusability of the catalyst material used.

It is therefore an object of the present invention to at least partially overcome the disadvantages known from the prior art. In particular, the object of the present invention is to provide a process enabling efficient conversion of olefins that are difficult to hydroformylate and, in addition, a simple and efficient separation of the reaction solution accompanied by improved catalyst re-use.

The problem is solved by the feature of the independent method claim. Preferred aspects of the invention appear in the dependent claims, the description or the drawings, and the further features described or shown in the dependent claims or the description or the drawings, individually or in any way, unless the context clearly dictates otherwise. The combination of can constitute the object of the present invention.

According to the present invention, the problem is a process for producing aldehydes by hydroformylation of olefins with synthesis gas over a transition metal complex catalyst, wherein, in a first process step, the olefins are converted to a metal and a metal in the presence of a water-miscible solvent. reacted by a water-soluble transition metal complex catalyst composed of a ligand bound thereto, the pressure, temperature and ratio of the solvent and aqueous catalyst solution are controlled so that the hydroformylation is carried out in a homogeneous single-phase reaction solution, and the second step step, by lowering the temperature and/or lowering the pressure, the homogeneous reaction solution from the first reaction step is converted into a two-phase process solution and at least a portion of the organic phase is separated from the aqueous phase.

Surprisingly, a number of different olefins can be highly selectively converted to the corresponding aldehydes using the process according to the invention in a controlled single-phase reaction environment with an aqueous catalyst component, whereby one or more double bonds and/or It has been found that high conversions are achieved within a short process time even when difficult-to-react olefin starting materials having one or more ring structures are used. Besides highly efficient conversion within the reaction environment, the controlled composition of the reaction environment also facilitates to a great extent the work-up of the reaction solution after completion of the reaction. A further advantage is that the desired organic product and the catalyst solution can be readily thermally and gently separated, making the cost-intensive catalyst easily reprocessable and reusable without significant loss of reactivity and materials. Without being bound by theory, it appears that the single-phase reaction environment protects the catalyst, and more specifically the organic ligands of the catalyst complex, from premature degradation under given reaction conditions. In addition, the controlled transfer of the reaction solution into the two-phase system over the organic product and the aqueous catalyst in the second process step results in a significant reduction of the catalytic system in the work-up, both in higher recoverable amount and activity of the catalyst compared to other catalyst work-up processes. It seems to prevent losses. This is especially true when compared to reactions in pure organic phases where recovery of the catalyst, which is not water soluble, is difficult. The water-soluble catalyst is separated from the organic product phase by mechanical separation of the aqueous catalyst phase after the reaction. Thus, the water-soluble catalyst system is not subject to thermal stress unlike distillative separations for reactions in the pure organic phase. High and sustained thermal loads on catalysts often result in their deactivation. In this regard, the coupling of the two process steps according to the present invention has a synergistic effect, which promotes highly efficient catalyst-protected conversions in large-scale industrial environments.

The process according to the present invention is a process for producing aldehydes by hydroformylation of olefins with synthesis gas over a transition metal complex catalyst. The starting material may be an olefin or mixture of olefins having from 4 to 24 carbon atoms, preferably from 6 to 20 carbon atoms, more preferably from 8 to 20 carbon atoms. The mixture may comprise or consist of olefins having one or more terminal and/or internal C-C double bonds. The mixture may comprise or consist of olefins having the same, similar (±2) or significantly different (>±2) number of carbon atoms (C number). These may be straight chain, branched chain or cyclic olefins. The olefin may be an aliphatic olefin with no or at least one ring structure. Thus, an olefin may have one, two, three or more rings in its molecule, and the double bond may be present in or on the ring structure. Usually, these olefins react incompletely in conventional hydroformylation processes. Aldehydes (HC=O) are obtained from these olefins by reaction with syngas, ie hydrogen and carbon monoxide, and the C-number of the olefin is increased by one by the reaction.

In the hydroformylation step of the first process step, preferably a synthesis gas of carbon monoxide and hydrogen is used, and the molar ratio of carbon monoxide to hydrogen is preferably from 1:4 to 4:1, more preferably from 1:2 to 2 :1, most preferably from 1:1.2 to 1.2:1. In particular, synthesis gas may be used in which there is an approximate stoichiometric ratio of carbon monoxide to hydrogen.

In a first process step, an olefin is reacted using a water-soluble transition metal complex catalyst comprising a metal and a ligand bound thereto. Applicable hydroformylation catalysts include a metal and one or more ligands coordinated to the metal. As such, the catalyst may be added preformed to the reaction environment or the active catalyst may form in situ under reaction conditions from another metal source, such as a metal salt, in the reaction zone. The latter is by addition or exchange of ligands present in the reaction zone, such as, for example, CO, hydrogen or organic complex ligands. Preferably, the transition metal complex catalyst may be a metal of subgroups 8 to 10 of the periodic table, in particular Co, Ru, Rh, Pd, Pt, Os or Ir, more particularly Rh, Co, Ir or Ru. Thus, the water solubility of the catalyst complex is essentially co-determined by the choice of the ligand, and the catalyst is water soluble according to the present invention if the water solubility of the catalyst at 20° C. is greater than or equal to 100 g/L. Solubility can be determined, for example, according to the OECD method ("OECD Guideline For The Testing Of Chemicals", "Water solubility", 27 July 1995). The ligand can be an inorganic counterion such as a halogen or a more complex organic molecule such as an acetate or aromatic complex ligand containing one or more heteroatoms.

In the first stage of the process, the reactants are reacted in the presence of a water-miscible solvent. The hydroformylation of olefins through the addition of syngas to the aldehyde takes place in the presence of an additional solvent other than water. Preferred solvents can be liquids that are at least partially soluble in water. The water solubility of such a solvent may be, for example, 20 g/L or more at 20°C. Suitable solvents in this group may be, for example, lower monoalcohols or diols. The solvent may also preferably be completely miscible with water. The use of solvents with this solubility ratio in water can help to obtain particularly robust single-phase regions that can reliably compensate pressure and/or temperature fluctuations that may occur. In addition, the use of this family of solvents can help compensate for large changes in composition due to product formation. In addition, the proportion of the solvent can be kept sufficiently small, so that the separation of the resulting mixture is easy and the energy cost for separation is kept low.

The pressure, temperature, and ratio of solvent and aqueous catalyst solution are controlled in the first process step so that hydroformylation is carried out in a homogeneous single-phase reaction solution. Due to the presence of the aqueous catalyst solution, the non-water soluble olefinic reactants and the slightly water soluble aldehyde product, a two-phase solution is formed in the reaction zone under reaction conditions without further action, as opposed to efficient conversion of the reactants. With the addition of additional solvent, depending on the amount of aqueous catalyst under reaction conditions, i.e., the amount of solvent, the amount of reactants, or the amount of products/intermediates, there will be single-phase or two-phase regions in the phase diagram. can The change between the single-phase or two-phase regime can be controlled using the amount, particularly the amount of aqueous catalyst and the amount of solvent, so that the reaction always proceeds in the single-phase regime under given pressure and temperature conditions. By using the correct ratio of the amount of catalyst aqueous solution and the amount of solvent together with the correct solubility or miscibility of solvent and water, the reaction can proceed in the single-phase range even if the ratio of intermediate to final product is changed or increased. For example, control can be exercised by specifying the ratio of the solvent to the aqueous catalyst solution at the start of the reaction. However, it is also possible to adjust the amount of one or the other component during the course of the reaction so that the phase equilibrium always runs in the single-phase regime. The latter mode of operation can be carried out, for example, by controlled addition of solvent to the reaction zone tailored to the amount of product formed. Basic mono- or biphasic phase ranges of phase equilibrium can be found in the literature and can be calculated (see Figure 1) or reasonable by orienting experiments with varying compositions of selected catalysts in aqueous solutions, solvents and reactants/products under reaction conditions. can be determined through effort.

In the second process step, by lowering the temperature and/or lowering the pressure, the homogeneous reaction solution from the first reaction step is converted into a two-phase process solution and at least part of the organic phase is separated from the aqueous phase. From a set of possible single-phase compositions of aqueous catalyst solution, solvent and olefinic reactants/products, under selected reaction conditions, by simple orientation experiments, possible compositions that result in changes in phase ranges due to changes in temperature and/or pressure. It is possible to determine a subset. Such a composition can fall into a suitable and biphasic state at the end of the reaction by a simple change in the reaction conditions, allowing a simple separation between the organic and aqueous phases to occur. This portion of the single-phase region is generally closer to the phase boundary between the single-phase region and the two-phase region and phase separation as a function of pressure and/or temperature conditions may follow, for example purely visually. Separation of the two phases can be carried out, for example, through purely mechanical steps such as decantation. However, it is also possible for the two phases to be separated from each other via purely thermal separation methods without mechanical separation. Due to the two-phase nature of the reaction solution, thermal separation can also be performed in a simpler and more resource efficient manner. Of course, for work-up purposes it is also possible to combine the mechanical separation operation with the thermal separation operation, so that the thermal load on the catalyst system is low due to the low boiling point of the solvent selected in the process according to the invention.

In a preferred embodiment of the method, the temperature and pressure can be kept constant during the reaction and the single phase of the reaction solution can be adjusted through the mass ratio of solvent to aqueous catalyst solution. It has also been found advantageous that the desired single-phase range is essentially tuned through the mass ratio of catalyst aqueous solution to solvent. Since "safe" phase ranges can be obtained here, changes in composition during the reaction due to the formation of intermediates and/or final products and formation of high molecular weight by-products can be reliably compensated. In addition, the selection of a suitable solvent and solvent amount in relation to the aqueous catalyst solution may be used to compensate for any temperature and/or pressure fluctuations that may occur during the course of the reaction. Through this determination, the entire reaction can be stably maintained in the single-phase range. Further preferably, this control can be determined by the choice of the amount of solvent and aqueous catalyst solution at the beginning of the reaction.

In a preferred embodiment of the method, the first process step may be carried out at a pressure of 0.5 MPa or more and 10 MPa or less and at a temperature of 70 °C or more and 150 °C or less. This temperature interval has been found to be particularly advantageous because the reactivity with syngas is increased by operating in the single-phase range. In this range, a particularly rapid and selective conversion is obtained, whereby the proportion of particularly formed high-boiling substances can be kept very low. In addition, the catalyst lifetime is significantly extended, which may be due to reduced degradation of the ligands in the reaction solution. Surprisingly, even low pressures within this temperature range were found to be sufficient for conversion of the difficult reactants. This is particularly true for dual reactions when sterically challenging reactants or diolefin reactants are used. Even in this reaction, the aqueous component of the single-phase region does not appear to inhibit the inflow of synthesis gas, thus ensuring sufficient gas inflow into the reaction solution even at an overall lower pressure.

In a further preferred aspect of the invention, the olefin may have at least two non-conjugated double bonds. The process according to the invention is particularly suitable for reactions of challenging reactants which may have, for example, two or more isolated double bonds. Reaction of two double bonds within a single-phase reaction was also found to be possible. This is surprising because reactions carried out in the biphasic range generally allow conversion of only one double bond. Also, compared to a two-phase reaction, a single-phase reaction may be faster and more selective and may have a lower proportion of high-boiling by-products. The double bonds in dienes can be present in aliphatic chains and/or rings. Preferably, short or medium chain aliphatic diolefins or higher olefins may be reacted. Therefore, it is possible to react olefins having two or more unsaturated bonds having a molecular weight of 50 g/mol or more and 500 g/mol or less.

[0028] In a preferred characteristic of the process, the olefin may have at least one aliphatic ring. It has been found to be particularly advantageous that sterically difficult to react olefin starting materials with rigid aliphatic ring structures can also be reacted within the single-phase process according to the invention. Usually, these olefins react much worse with catalysts than short aliphatic chains in solution or in the case of multiple double bonds are stopped at intermediate stages. Reactants may be monocyclic or polycyclic. Although single-phase reactions in pure organic solvents and pure organic phases are possible, problems in the purification of the obtained products increase. In addition, the latter reaction shows problems with catalyst recovery and lifetime. For example, in reactions in pure organic solvents, unmodified (no ligand added) metal catalysts are also used for the reactions of the diolefins mentioned herein, which require a large amount of catalyst and the catalyst is not recycled. . When ligand-metal complexes are used as catalysts, the desired activity for hydroformylation of polycyclic diolefins is often not achieved. The monocyclic, bicyclic or tricyclic olefin comprises two or three closed non-aromatic rings which may further preferably have a molecular weight of greater than or equal to 60 g/mol and less than or equal to 450 g/mol.

In a further preferred embodiment of the method, the molar ratio of water in the aqueous catalyst solution used to catalyst metal, expressed as moles of water in the aqueous catalyst solution used divided by moles of catalyst metal, may be greater than or equal to 5000 and less than or equal to 60000. Despite the fact that the access of the organic reactants to the catalyst should be enhanced by a more organic environment, the ratio of water to catalyst has been found to be particularly advantageous. With this ratio of water, complete conversion of the diene reactant to dialdehyde is achieved and process control can be safely designed into a single phase. In addition, fluctuations in reaction conditions can be safely compensated without leaving the single-phase regime. It also appears that this water-catalyst metal ratio is suitable for enabling safe and complete separation of the aqueous catalyst phase in the second process step. Due to this water ratio, both the catalyst and its ligands are sufficiently protected in a single-phase reaction. In addition, a sufficient aqueous environment can be maintained even after changing reaction conditions and decomposition of a single-phase reaction into a two-phase reaction, promoting reusability of the catalyst solution.

According to a further preferred embodiment of the method, the metal of the water soluble transition metal complex catalyst may be rhodium and the ligand comprises a water soluble diphosphine or triarylphosphine. The catalyst used or the catalyst system formed in the reaction solution contains the transition metal rhodium. These metals can allow particularly fast reaction kinetics in single-phase solution and can also safely convert sterically difficult polyenes or olefins with rigid ring structures. In addition to the metal, the catalyst has in its coordination sphere at least one diphosphine ligand with two phosphorus atoms or at least one organic triarylphosphine ligand with one phosphorus atom, or in a reaction solution under reaction conditions. betray them A catalytically active system is further formed under reaction conditions by adding additional hydrogen and carbon monoxide to the reaction solution, and components of the syngas form coordination complexes with metals. However, it is also possible to first preform the catalyst and then feed it to the actual hydroformylation stage. In this case, the preformation conditions generally correspond to the hydroformylation conditions.

For example, triarylphosphine may have the formula

In the above formula, Ar ₁ , Ar ₂ and Ar ₃ represents the same or different aryl groups containing 6 to 14 carbon atoms. Substituents Y ₁ , Y ₂ and Y ₃ represents identical or different straight-chain or branched-chain alkyl or alkoxy groups of 1 to 4 carbon atoms, chlorine, bromine, hydroxyl, cyanide or nitro groups, and additionally amino groups of the formula NR ¹ R ² , wherein the substituent R ¹ and R ² can be the same or different and represents hydrogen, a straight-chain or branched-chain alkyl group containing 1 to 4 carbon atoms. The counter anion M may represent lithium, sodium, potassium, magnesium, calcium or barium, m1, m2 and m3 may be the same or different and represent an integer from 0 to 5, n1, n2 and n3 are the same or different and represent 0 to 3, and at least one of the numbers n1, n2 and n3 is 1 or greater. The triarylphosphine complex catalyst is a water-soluble triarylphosphine complex catalyst having a water solubility of 100 g/L or more at 20°C.

In the water-soluble triarylphosphine of the above formula, preferably, the Ar ₁ , Ar ₂ , Ar ₃ groups are phenyl groups, Y ₁ , Y ₂ and Y ₃ includes a triarylphosphine representing a methyl group, an ethyl group, a methoxy group, an ethoxy group and/or a chlorine atom. The cationic moiety M of the inorganic cation may preferably be sodium, potassium, calcium and barium. In particular, suitable water-soluble triarylphosphines are such that Ar ₁ , Ar ₂ , Ar ₃ each represent a phenyl group, m1, m2, m3 are 0, n1, n2 and n3 are 0 or 1 and n1+n2+n3 together 1 to 3, and the sulfonate group may preferably be a compound which may be in the meta position. Ligands can be used by themselves or as a mixture. Suitable examples of water-soluble triarylphosphine ligands include (sulfophenyl)-diphenylphosphine, di(sulfophenyl)phenylphosphine and tri(sulfophenylphosphine). In the prior art, (sulfophenyl)diphenylphosphine is abbreviated as TPPMS, di(sulfophenyl)phenylphosphine as TPPDS, and tri(sulfophenyl)phosphine as TPPTS. These ligands can contribute to sufficient water solubility of the catalyst complex and are stable in both single-phase and two-phase systems.

The sulfonated diphosphines of formulas (III) and (IV) are also suitable as water-soluble diphosphines.

In formula (III), each of n4 and n5 is independently 0 or 1, and compounds of formula (III) may contain up to 6 —SO ₃ M groups.

In formula (IV), each of n6, n7, n8 and n9 is independently 0 or 1, and the compound of formula (IV) contains 4 to 8 —SO ₃ M groups.

In formula (III) and formula (IV), M represents ammonium, a monovalent or multivalent metal equivalent, in particular sodium, potassium, calcium or barium.

In a preferred embodiment of the method, the mass ratio of the aqueous catalyst solution to the solvent, expressed as the mass of the aqueous catalyst solution divided by the mass of the solvent, may be 0.25 or more and 4 or less. In single-phase reaction solutions, this mass ratio has been found to be particularly safe and advantageous. This mass ratio can also be used to reliably compensate for compositional changes due to product formation and unavoidable fluctuations in pressure and temperature due to the method. With further advantage, relatively small amounts of solvent additives of at least 0.5 and at most 2, particularly preferably at least 0.75 and at most 1.5 can be obtained relative to the mass of the catalyst solution. This low solvent addition can contribute to a more efficient work-up of the reaction solution after completion of the reaction.

In a further preferred aspect of the method, the water-miscible solvent may have a solubility in water of at least 20 g/L at 20°C. Thus, to obtain the most stable single-phase range with the least addition of solvent, it has been found to be particularly suitable for the solvent to be miscible with water within the range indicated above. Such a single-phase reaction solution may be stable with respect to changes in the reaction environment caused by the added products and with respect to possible changes in the reaction parameters of pressure and temperature, and also in particular after completion of the reaction, the organic phase and the aqueous phase A desirable phase separation can be provided. In particular, the proportion of the recoverable catalyst after completion of the reaction can be increased by this solvent group. In a further preferred embodiment, the solubility of the solvent is at least 60 g/l, further preferably at least 70 g/l at 20°C, further Preferably it may be 80 g/l or more. In a further preferred embodiment, the solvent is completely miscible with water at 20°C.

In a preferred feature of the present invention, the solvent may be selected from the group consisting of straight or branched chain C2-C5 alcohols or mixtures of at least two alcohols from these groups. In particular, short-chain alcohols have been found to be particularly suitable for obtaining particularly efficient conversions in the single-phase region. With these solvents, reactants that are difficult to hydroformylate can also react highly selectively on a water-soluble catalyst in a very short process time. The service life of the catalyst may be significantly extended by this solvent selection. These solvents have a lower binding affinity for the metal compared to the ligand. At the same time, however, it can impart a stabilizing effect to the ligand, protecting it from degradation. A further advantage arises from the fact that very robust single-phase domains can be obtained with only a small amount of solvent fraction, reducing the cost of work-up and separation of the desired product. Solvent selection can also help to very quickly and completely change the system from single-phase to two-phase in the second process step to recover a significant portion of the catalyst and recycle it back into the reaction cycle if necessary. In addition, the low boiling point of the chosen solvent is advantageous, allowing for easy separation from the product or catalyst system if required.

In a further preferred aspect of the method, the solvent may be isopropanol. It has been found to be particularly advantageous to use isopropanol for single-phase conversion of olefins in the hydroformylation process. By adding isopropanol, even difficult-to-hydroformylate olefin products can be highly selectively converted over a water-soluble catalyst in a very short process time. The service life of the catalyst may be significantly extended by these solvents. A further advantage comes from the fact that the highly robust single-phase domains are formed with only a small amount of isopropanol, reducing the cost of processing and separation of the desired product. In addition, due to the physical difference of isopropanol to aldehyde product, a particularly simple and complete separation can be achieved after the end of the reaction. In particular, it can also prolong the recyclability of the catalyst.

In a further preferred embodiment of the method, the at least one ligand of the water soluble transition metal complex catalyst may comprise triphenylphosphine-3,3′,3″-trisulfonic acid sodium salt. Such triphenylphosphine The use of ligands has been found to be particularly advantageous for working in the single-phase regime. In addition to the highly selective conversion of the olefins used, even when the reaction time is long, a particularly small amount of high-boiling substances is formed. This is especially true for isopropanol as a solvent In this case, a particularly low degradation of the organic ligands occurs In addition, catalyst complexes having these ligands can be recycled particularly efficiently from the reaction mixture, for example by recycling them back into the reaction cycle in a continuous reaction. In addition, the degradation of these ligands appears to be particularly low in a single-phase reaction environment. In a further preferred embodiment, triphenylphosphine-3,3',3"-trisulfonic acid sodium salt is the only aromatic complex ligand in the reaction can be

In a further preferred embodiment of the method, the water soluble transition metal complex catalyst may comprise a triarylphosphine ligand and a catalytic metal, expressed as moles of triarylphosphine ligand divided by moles of catalytic metal, to the catalytic metal The molar usage ratio of the triarylphosphine ligand is 3 or more and 15 or less. For single-phase range reactions it has been found advantageous to keep the ratio of organic ligand to catalyst metal within a narrow range. Within these ratios, highly reproducible conversions occur with high selectivity. This may be because the lower the ligand concentration, the higher the catalytic activity. At the same time, degradation of organic ligands in single-phase solutions can be retarded or completely prevented. Thus, such process control can contribute to catalysts being used more frequently and for longer periods of time. This ratio also makes a greater contribution to protecting the catalyst even during work-up, improving the recovery of the catalyst after reaction product separation. Further preferably, the ratio may be 5 or more and 12 or less, more preferably 7 or more and 10 or less.

In a further preferred embodiment of the method, the mole ratio of catalyst metal to olefin, expressed as moles of catalyst metal divided by moles of olefin, may be greater than or equal to 0.05% and less than or equal to 0.75%. Single-phase reaction control may be used very effectively, especially with low catalyst to olefin feedstock ratios. Complete conversion to dialdehyde is achieved within a short reaction time and the catalyst life may also be longer compared to state-of-the-art solutions. The ratio may be further preferably 0.15% or more and 0.65% or less, more preferably 0.3% or more and 0.5% or less.

In a preferred embodiment of the process, in a second process step, the homogeneous reaction solution from the first reaction step can be converted to a two-phase process solution by lowering the temperature and the product aldehyde can be separated. In the second process step of the process according to the invention, after the olefins have been converted to aldehydes, the reaction pressure and/or reaction temperature can in principle be reduced. This forces the separation of the homogeneous reaction solution obtained in the first reaction step into a two-phase system. One phase contains the aqueous catalyst and the second phase contains the product aldehyde. In particular, the separation of the two phases, mainly by temperature, enables a gentle mechanical separation of the product from the catalyst. To this end, the pressure is changed significantly only after the temperature has changed by at least 50° C. from the temperature of the reaction zone. Significant changes in reaction pressure occur when there is a deviation of at least 10% relative to the reaction pressure. It is particularly advantageous if the pure thermal separation is not carried out in the form of distillation, in which higher boiling substances can advantageously be formed and the catalyst system can be deactivated. This is a process method carried out under mild conditions.

In a further aspect of the method, the pH of the aqueous catalyst solution may be greater than or equal to pH 4 and less than or equal to pH 10. By adjusting the pH to the preferred range, catalysts comprising transition metals and water-soluble organophosphorus ligands have been found to have very high activity and high selectivity for product formation. The adjustment can be carried out by known adjustment agents such as inorganic acids or bases on the catalyst solution used. However, it is also possible and advantageous for the homogeneous phase formed by the aqueous catalyst solution used to be maintained in the specified pH range. In addition, low degradation of the catalyst was also observed with favorable pH adjustments. In a further preferred embodiment, the pH may be adjusted to a pH greater than or equal to pH 5 and less than or equal to pH 8, further preferably greater than or equal to pH 5.5 and less than or equal to pH 7.

In a preferred embodiment of the process, the olefin used may be a polycyclic aliphatic diolefin selected from the group consisting of bicyclic or tricyclic dienes or mixtures thereof. A sterically difficult cyclic diene reactant with an internal double bond reacts significantly worse with the catalyst complex in solution than, for example, an aliphatic short chain, due to its rigid ring structure, and can be reacted within the process according to the invention. It has been found to be particularly advantageous. Polycyclic olefinic aliphatics can only be reacted very poorly in the two-phase region by conventional process routes. Although single-phase reactions are possible in pure organic solvents, the challenges in purification of the obtained products are increased. In addition, the latter reaction shows problems with catalyst recovery and its lifetime. For example, in reactions in pure organic solvents, unmodified (no ligand added) metal catalysts are also used for the reactions of the diolefins mentioned herein, where high catalyst loadings are required and the catalysts are not recycled. The use of ligand-metal complexes as catalysts often does not achieve the desired activity in the hydroformylation of polycyclic diolefins. The bicyclic or tricyclic diene that can be reacted according to the present invention comprises two or three closed non-aromatic rings and may further preferably have a molecular weight of greater than or equal to 60 g/mol and less than or equal to 450 g/mol.

In a further preferred embodiment of the method, the olefin may be a cyclic aliphatic diolefin selected from the group consisting of dicyclopentadiene or norbornadiene. With the reaction according to the present invention, tricyclo[5.2.1.0 ^2,6 ]deca-3,8-diene and bicyclo[2.2.1]hepta-2,5-diene are particularly difficult to react sterically. Polycyclic aliphatic olefins that are poorly soluble in water can react particularly efficiently. High conversions are achieved at high selectivity and catalyst systems can exhibit particularly long service lives and improved recoveries.

Figure 1 shows the results of the calculated phase behavior of a ternary mixture as a function of composition at a temperature of 120 °C.

Example

In the hydroformylation according to the present invention, dicyclopentadiene DCDP is converted to the corresponding dialdehyde by an organically modified rhodium complex catalyst in a homogeneous reaction solution according to the reaction equation:

The catalyst used is a water-soluble complex catalyst comprising a TPPTS organophosphorus ligand according to the formula:

Isopropanol is used as a solvent to achieve a single phase of the reaction system. The reaction is carried out in a stirred reactor vessel (800 rpm) at 130° C. and a pressure of 5 MPa within a reaction time of 3 hours.

The input amount of the reactants is as follows:

A catalytic aqueous solution of rhodium and ligand was prepared. Rh(OAc) ₂ was used as the rhodium source. This solution was added to the reactor along with the above amount of isopropanol. Dicyclopentadiene was added and reacted at 130° C. and 5 MPa syngas pressure for 3 hours. The reaction was stopped. After cooling and depressurizing the autoclave, isopropanol was removed from the reaction mixture at 100 mbar and 40°C. The residue was then placed in a phase separator to separate the catalyst and product phases. The product phase was analyzed by GC. The following composition was obtained (determined by GC):

The above results were obtained without considering the solvent content. The results show that almost 100% conversion was achieved with a very low catalyst concentration of 0.45 mol% based on diolefin. In addition, a TCD dial selectivity of about 90% was obtained.

DCPD was repeatedly converted to TCD by adding isopropanol to the single-phase region of the reaction solution. The experimental conditions in each case were as follows:

- 30 g DCPD per run

- Rh(OAc) ₂ 350ppm based on total mass of 300g

- P/Rh ratio = 10/1, equivalent to 18.38g of TPPTS in 135g of water

- 135g of isopropanol

- Reaction temperature: 130 ℃

- Reaction pressure: 50 bar

- Response time: 3 hours

The conversion and selectivity of the individual reactions correspond to the results given above within the margin of error. After completion of the reaction at 100 mbar and 40° C., isopropanol was removed from the reaction solution through a rotary evaporator and the residue was balanced. The remaining residue was then transferred to a phase separator and phase separation was performed at room temperature. The organic phase consisting of the reaction product was removed, balanced and sampled for rhodium content and product fraction. The upper aqueous catalyst phase was also omitted, balanced and recombined with isopropanol previously removed. Fresh DCPD was added to the combined catalyst phase and the mixture was re-reacted in a reactor at 130° C. and 50 bar pressure syngas for 3 hours. The reaction was repeated 5 times. This process was repeated 5 times.

The individual weights of the organic phases and their compositions are constant over the five runs, especially with respect to the TCD dial and the TCD monoenal. The proportion of rhodium in the organic phase is also constant and low. The amount of rhodium in the organic phase per run is about 3.2 ppm%±0.8 ppm% based on the total rhodium input. Thus, it can be shown that in addition to the successful conversion of polycyclic diolefins that are difficult to hydroformylate, the process according to the present invention also enables very efficient and simple recovery and reuse of the catalyst.

Figure 1 shows the results of the calculated phase behavior of a ternary mixture as a function of composition at a temperature of 120 °C. The components are an aqueous solution of the Rh-TPPTS complex catalyst (bottom left), isopropanol as solvent (top) and the final product TCD dial (bottom right). The dotted line area contains the mass fraction of the three-component composition that is biphasic at that temperature. In the region at the top of the triangle without dotted lines, there is a single-phase composition under pressure and temperature conditions. Since the solubility of the olefin reactants does not differ significantly from the solubility of the intermediates and final products, these phase equilibrium diagrams represent the entire reaction with varying reactant/product ratios.

Additional tests were performed with other solvents and reactants. The test conditions for this test are as follows:

In contrast to the reaction conditions given above, n-propanol was used instead of isopropanol. Without optimizing the experimental conditions for using n-propanol, the reaction of dicyclopentadiene gave a TCD dial product fraction of 61.3% and an olefin conversion of 99.9%. This shows that the reaction can also be carried out with an unbranched alcohol as a solvent.

The reaction was repeated under the same process conditions as above. Meanwhile, 20 g of methylcyclohexane (MCH) was further added as a solvent. Without optimizing the experimental conditions for using this solvent mixture, the TCD dial product fraction is 69.15% and the olefin conversion is 99.5%. This shows that the reaction can also be carried out in solvent mixtures.

The reaction was repeated under the same process conditions as above. Unlike the above reaction, 1-octene is now used as the olefin component instead of dicyclopentadiene. Without optimizing the experimental conditions to use different olefins, the yield of the C9 aldehyde target component is 83.6% and the olefin conversion is 98%. This shows that the reaction can also be carried out with non-cyclic monoolefins.

Claims (15)

A process for producing an aldehyde by hydroformylation of an olefin with synthesis gas over a transition metal complex catalyst, comprising:
- in a first process step, the olefin is reacted with a water-soluble transition metal complex catalyst comprising a metal and a ligand bound thereto in the presence of a water-miscible solvent, wherein the pressure, temperature and ratio of the solvent and aqueous catalyst solution are The hydroformylation is controlled to be carried out in a homogeneous single-phase reaction solution;
- in the second process step, by lowering the temperature and/or lowering the pressure, the homogeneous reaction solution obtained from the first reaction step is converted into a two-phase process solution and at least part of the organic phase is separated from the aqueous phase. How to do it. The method according to claim 1, wherein temperature and pressure are kept constant during the reaction, and the single phase of the reaction solution is adjusted through the mass ratio of the solvent to the aqueous catalyst solution. The method according to claim 1 or 2, wherein the first process step is performed at a pressure of 0.5 MPa or more and 10 MPa or less and a temperature of 70 °C or more and 150 °C or less. 4. The method according to any one of claims 1 to 3, wherein the olefin has at least two non-conjugated double bonds. 5. The method of any one of claims 1 to 4, wherein the olefin comprises at least one aliphatic ring. 6. The method according to any one of claims 1 to 5, wherein the molar ratio of water in the aqueous catalyst solution used to catalyst metal, expressed as moles of water in the aqueous catalyst solution used divided by moles of catalyst metal, is at least 5000 and not more than 60000. , method. 7. The method according to any one of claims 1 to 6, wherein the metal of the water soluble transition metal complex catalyst is rhodium and the ligand comprises a water soluble diphosphine or triarylphosphine. 8. The process according to any one of claims 1 to 7, wherein the mass ratio of the aqueous catalyst solution to the solvent, expressed as the mass of the aqueous catalyst solution divided by the mass of the solvent, is at least 0.25 and at most 4. 9. The method according to any one of claims 1 to 8, wherein the water-miscible solvent has a solubility in water of at least 20 g/L at 20°C. 10. The method according to any one of claims 1 to 9, wherein the solvent is selected from the group consisting of straight or branched chain C2-C5 alcohols or mixtures of at least two alcohols from these groups. 11. The method of any one of claims 1 to 10, wherein the solvent is isopropanol. 12. The process according to any one of claims 1 to 11, wherein the at least one ligand of the water soluble transition metal complex catalyst comprises triphenylphosphine-3,3',3"-trisulfonic acid sodium salt. . 13. The method according to any one of claims 1 to 12, wherein the water soluble transition metal complex catalyst comprises a triarylphosphine ligand and a catalytic metal, expressed as moles of triarylphosphine ligand divided by moles of catalytic metal. , the molar usage ratio of the triarylphosphine ligand to the catalytic metal is 3 or more and 15 or less. 14. The process according to any one of claims 1 to 13, wherein the molar ratio of catalyst metal to olefin, expressed as moles of catalyst metal divided by moles of olefin, is greater than or equal to 0.05% and less than or equal to 0.75%. 15. The method according to any one of claims 1 to 14, wherein the pH of the aqueous catalyst solution is greater than or equal to pH 4 and less than or equal to pH 10.